1. Field of Invention
The present invention relates to an emergency locking device for a vehicle seat or an automotive seat, and in particular to an emergency locking device for locking quickly a seat back against movement relative to a seat cushion in the seat, in the case of a sudden collision or deceleration.
2. Description of Prior Art
FIG. 1 shows a typical, conventional seat framework with one reclining device for a vehicle or automotive seat, which is-basically formed by: a seat cushion frame (8) forming a seat cushion of the seat; a generally inverted-U-shaped seat back frame (7) which forms a seat back of the seat, having one lower flattened end (70) at one lateral frame section (7a) thereof; a pair of slide rails (Sa)(Sb); a connecting bracket (2) which is fixed on one of the two slide rails (i.e. Sb) and penetrates through one rearward side portion of the seat cushion frame (8), projecting its upper end portion to which the lower fattened end (70) of seat back frame (7) is rotatably connected via a hinge pin (6); and a reclining device (RD) by means of which the lower end of another lateral frame section (7a) of the seat back frame (7) is rotatably connected to another rearward side portion of the seat cushion frame (8). In this type of seat, the seat back frame (7) (i.e. seat back) can be adjusted in inclination angle, forwardly and backwardly, with respect to the seat cushion frame (8) and locked at a desired inclination angle by operation of the reclining device (RD).
However, in the case of such seat with one reclining device, if great forward and backward loads (FL) (BL) are applied to the seat back frame (7) locked by the reclining device (RD) in a collision or the like, it is highly possible that the foregoing one lateral frame section (7a), namely an unlocked portion, will be deformed, which will further give a great damage or injury to an occupant sitting on the seat.
To solve such problem, one can suggest a seat of a double reclining device type, wherein two reclining devices are provided respectively at both lateral frame sections of seat back frame to permit locking and protecting them against deformation. But, it is defective in increasing a whole weight of the seat and, in most cases, both reclining devices are not easily worked simultaneously, leaving a problem with the synchronized operation of both reclining devices.